1. •The meaning of the word ecology was given by German
Biologist Ernst Haeckel in 1869.
•The word ecology is derived from Greek words ‘Oikos’
meaning house, habitat or place of living and ‘Logos’
meaning to study.
•Ecology is defined as the study of interrelationship and
interaction of different organisms with each other and with
their environment. It is concerned with the general principles
that apply to both animals and plants.
•Ecology is the study of ecosystems
Ecology
Objectives/Scope of Ecological Studies
•It is important for humanity to understand its environment because we have the
ability to modify the environment through the use of technology. Therefore, ecology is
more than just the understanding of the interrelationships between organisms and
their environment; it also has social, political, economic and technological dimensions.
•It also is a study of evolutionary development of organisms, the biological
productivity and energy flow in the natural system.
•To develop mathematical models to relate interaction of parameters and to predict
the effects
2. Approaches to the study of ecology (according to Smith)
•System ecology,
•Theoretical ecology and
•Evolutionary ecology.
System ecology is concerned with analysis and understanding of structure and
functions of the ecosystem using applied mathematics. It involves the construction of
models that represent the real system for the purpose of experimentation. The model
should mimic the real system at least over some restricted range.
Theoretical ecology involves modeling of mainly the populations a focusing mainly on
areas like predation, competition, niche theory, diversity and stability of a community
structure. It utilizes the theories and equations developed in pure mathematics.
The evolutionary ecology is concerned primarily with the interactions between the
organism and their biological and physical environment as expressed in adaptations.
Adaptations through natural selection allow a species to reproduce successfully under
the given set of environmental conditions.
All the three approaches are interrelated and are essential for the complete
understanding of the subject of ecology.
3. Classification of Ecology
Based on level of organization:-
Based on kinds of organism:-
•Animal ecology,
•Plant ecology,
•Insect ecology
•Microbial ecology
•Autecology : It deals with the study
of an individual species of
organisms and it’s population. The
ecologists study the behavior and
adaptations of particular species to
the environmental condition at
every stage of that individual’s life
cycle. It is also called the Species
ecology.
Through the concept of Tansley
(1935) the divergence between autecology
and synecology were brought together.
The concept states that “all
organisms are interacting with one another
and also with the abiotic elements of their
environment in an interrelated system.
This means that organisms and
environment form a reciprocating system.
•Taxonomic ecology- It is concerned
with the ecology of different taxonomic
groups, viz. microbial ecology,
mammalian ecology, insect ecology and
so on.
•Synecology : It deals with the study of
communities, their composition, their
behavior and relation with the
environment. It is also called as Ecology
of communities.
4. Based on Environment or habitat ecology:-
1) Aquatic ecology : The study of
interaction of organisms in the water
1) Marine water ecology
i) Ocean
ii) Deep Sea
iii) Estuary
2) Freshwater Ecology
i) Letic (Running water)
a) River
b) Stream
c) Spring
ii) Lentic (Standing Water)
a) Pond
b) Lake
From this concept therefore emanates three main levels of integration in ecology:
i. Individual
ii. Population – Communnity
iii. Ecosystem
These are referred to as the basic units of ecology especially the ecosystem.
There is a give and take between these two systems with the action or inaction of
one system having impact on the other system.
Fresh water river Coral reefs
5. 2) Terrestrial Ecology : The study of interaction of organisms on land :
a. Grassland Ecology
b. Forest Ecology
c. Desert Ecology
Forest
Ecology
Ecology can also be classified on the basis of:
•the geographic or climatic area-
e.g. arctic ecology, tropical ecology
•the spatial scale under consideration-
e.g. macroecology, landscape ecology;
•the philosophical approach
e.g. systems ecology which adopts
a holistic approach;
•the methods used-
e.g. molecular ecology.
6. •Population ecology- It deals with the growth, trophic structure, metabolism and
regulation of a population..
•Community ecology- It deals with the ecology of different populations in the
same habitat and same environmental conditions.
•Ecosystem: abstraction of many separate ecosystems with similar characteristics.
•Habitat ecology- It includes the study of animals and plants in different habitats.
According to habitat, it can be further divided into freshwater ecology, marine ecology,
terrestrial ecology, forest ecology and desert ecology.
•Human ecology- It deals with the effects
of human activities on environment and
vice versa.
•Applied ecology- It deals with the
application of ecological concepts to
human needs including wild life
management, biological control, forestry
and conservation of natural resources.
Sub-Classification of Ecology
7. •Chemical ecology- It is concerned with the chemical affinity or preferences shown by
different, organisms.
•Physiological ecology (ecophysiology)- Physiological adaptation according to ecological
conditions are dealt in ecophysiology.
• Palaeo-ecology- It deals with the environmental conditions and life of the past ages.
Palaeontology and radioactive dating have aided significantly in the study of palaeo-ecology.
• Evolutionary ecology- It deals with evolutionary problems like speciation and segregation.
•Gynaecology (ecological-genetics)- Relationship of environment with genetic variability
are considered in gynecology.
• Eco-geography- It studies the geographical distribution of plants and animals in different
environments—collectively called as biomes.
• Pedology - It deals with the study of soil and refers to its nature like acidity, alkalinity,
humus contents, mineral contents, soil types and so forth.
• Ethology - It is the study of animal behavior in different environments under their natural
conditions.
•Sociology- When ecology and ethology are combined it becomes sociology.
•System ecology- When the structure and function of an ecosystem is analysed using
applied mathematics, statistics or computer, it is called as system ecology.
8. Even though the human civilization has so many revolutions but
all other living objects abide by the rules of nature superimposed by the
anthropogenic factors. Human beings can make some rules and try to
follow them but the nature is very messy and has so many exceptions to all
the rules. Therefore, in ecology there are principles with many exceptions
and not the rules.
According to Robert Leo Smith , the study of ecology primarily
concentrates on its unit structure ecosystem and he proposed the
principles of ecology.
Some of them are as given below:
1. Ecosystem is the major ecological unit. It contains both biotic and
abiotic factors through which nutrients are cycled and energy flows.
2. To permit these nutrient cycles and flow of energy the ecosystem must
possess a number of interrelated structural components such as soil,
water, nutrients, producers, consumers and decomposers.
3. The flow of energy and nutrient cycles are the functional components
of the ecosystem.
Ecological principles
9. 4. The total amount of energy that flows through the natural ecosystems depends upon
the amount fixed by producers (plants). The transfer of energy follows the laws of
thermodynamics and as it is passed from one feeding level to another, a portion of it is
lost. This limits the number of organisms at each feeding level as well as the total number
of feeding levels.
5. The ecosystems change from simple and unstable towards complex and stable with
time (Succession). Anthropogenic and natural exploitation (sudden environmental
changes) may reduce the rate of change.
6. Populations are the main functional units in the ecosystem.
7. Species diversity is related to the physical environment. More complex ecosystems
showing vertical stratification have greater biodiversity than the simple ones. For example
a forest is more rich in fauna and flora than a grassland.
8. Moderate and predictable environment holds more number of species than harsh and
unpredictable environment.
9. The ecosystems are historical : the present is related to the past and the future is
related to present.
10. An ecosystem is a community of living
organisms in conjunction with the nonliving
components of their environment (things
like air, water and mineral soil), interacting
as a system. These biotic and abiotic
components are regarded as linked
together through nutrient cycles and
energy flows. As ecosystems are defined by
the network of interactions among
organisms, and between organisms and
their environment, they can be of any size
but usually encompass specific, limited
spaces.
Ecosystem
The term Ecosystem was first proposed
by A.G. Tansley in 1935. he defined it as
“the system resulting from the
interaction of all the living and non
living factors of the Environment
Scales of Ecosystems
Micro:
A small scale ecosystem such as a pond, puddle, tree trunk, under a rock etc.
Messo:
A medium scale ecosystem such as a forest or a large lake.
Biome:
A very large ecosystem or collection of ecosystems with similar biotic and abiotic factors
12. 1. Abiotic
• Consists of Non-living chemical & physical components such as Al, Co, Zn, Cu,
C, H, O, P, K, N, and water, air, nutrients in the soil or water & Solar Energy
resptively.
• Physical & chemical factors that influence living organisms in land (terrestrial)
ecosystem & aquatic life zones.
• Abiotic factors can act as LIMITING FACTORS that keep a population at a
certain level.
Abiotic Components are mainly of two types:-
1) Climatic Factors:
which include rain, temperature, light, wind, etc.
2) Edaphic Factors:
which include soil, pH, Topography, Minerals, etc.
2. Biotic factors
• All the living things that directly or indirectly affect the ecosystem
biotic factors interact with other living organisms and the physical
environment can also be Limiting Factors ex. disease (bacteria), predators,
food resources.
• Made up of biological components consisting of living and dead plants,
animals and microorganisms.
13. The Major Biological Components of Ecosystem :
1) Producers (Autotrophs)(self-feeders)
•Make their own food from compounds that are obtained from their environment.
•Are the source of all food in an ecosystem.
•On land most producers are green plants.
•In freshwater and marine ecosystems, algae and plants are the major producers near
shorelines.
•In open water, the dominant producers are phytoplankton (most of them microscopic)
that float or drift in the water.
•Most producers capture sunlight to make carbohydrates (such as glucose) by
photosynthesis . 2) Consumers (Heterotrophs) (“other feeders”)
Get their energy and nutrients by feeding on other organisms
or their remains.
i. Primary consumers : Are those that eat producers
(plants) as a source of food. They are also known as
herbivores.
ii. Secondary consumers or carnivores : Eat other animals.
iii. Tertiary Consumers : Large Carnivores which feed on
secondary consumers.
iv. Quaternary Consumers : Largest Carnivores that feed on
tertiary consumers. They are not eaten by any animals.
v. Omnivores : Have mixed diet that include both plants and
animals.
14. 3)Decomposer :
• Mostly certain types of bacteria and fungi
are specialized consumers that recycle
organic matter in ecosystems.
•They do this by breaking down
(biodegrading) dead organic material to get
nutrients and releasing the resulting simpler
inorganic compounds into the soil and
water, where they can be taken up as
nutrients by producers.
Types of Ecosystem
1) Natural Ecosystems
2) Artificial (Man Engineered) Ecosystems
15.
16. 1. Natural Ecosystems : These
operate under natural conditions
without any major interference
by man.
i. Terrestrial Ecosystem :
Forest, grassland, desert,
etc.
ii. Aquatic Ecosystem :
a. Fresh water : Lotic
(running water like
spring, stream, or
rivers) or Lentic
(standing water as lake,
pond, pools, etc.)
b. Marine water : Such as
deep bodies as ocean or
shallow ones as Sea or
an estuary.
Lentic (standing water)
lake ecosystem
Lotic (flowing water)
river ecosystem
2. Artificial (Man Engineered) Ecosystems
: These are maintained artificially by
man where by addition of energy and
planned manipulation, natural balance
is disturbed regularly e.g., crop land
ecosystem.
Crop land
ecosystem
18. What is a Biome?
Biomes are very large ecological areas on the
earth’s surface, with fauna and flora (animals and plants)
adapting to their environment. Biomes are often defined
by abiotic factors such as climate, relief, geology, soils
and vegetation.
A biome is NOT an ecosystem, although in a
way it can look like a massive ecosystem. If you take a
closer look, you will notice that plants or animals in any
of the biomes have special adaptations that make it
possible for them to exist in that area. You may find
many units of ecosystems within one biome.
There are five major categories of biomes on
earth. In these five, there are many sub-biomes, under
which are many more well defined ecosystems.
